The history of Terceira Island is incredibly rich and filled with events that have influenced both national and international history.

Terceira island was formed by volcanic eruptions that occurred approximately 15 million years ago. These eruptions created an island with a diverse landscape including mountains, plateaus, and valleys.

There is no archaeological evidence to confirm human presence on the island before the 15th century. However, it is possible that prehistoric peoples from mainland Europe may have visited the island in search of natural resources.

The discovery of Terceira Island by Portuguese navigators likely took place between the late 1420s and early 1430s. Initially, it was called the Island of Jesus Christ, but its name was later changed to Terceira to reflect the order of earlier discoveries, Santa Maria and São Miguel.

Settlement on the island began in the 15th century with the arrival of Portuguese, Azorean, and Madeiran settlers. These settlers brought with them livestock, seeds, and tools, and they began cultivating the land and raising animals.

The city of Angra do Heroísmo was founded in 1432 and became the capital of the Azores archipelago. The city was built around a protected bay, making it an important port of call for Portuguese fleets departing for the New World.

Later, Terceira Island played a significant role in Portuguese exploration. Angra do Heroísmo was an important stopover for Portuguese fleets heading to the New World. During this period, the island also served as a significant center for trade and agricultural production. It was a major producer of wheat, corn, wine, and olive oil.

Terceira Island continued to thrive into the modern era. The city of Angra do Heroísmo was declared a UNESCO World Heritage site in 1983.

Today, Terceira Island is an important cultural and tourist center known for its natural beauty, history, and culture.

Another significant historical curiosity of Terceira Island is that Angra do Heroísmo served as the capital of Portugal twice, during the succession crisis of 1580 and the Portuguese Civil War (1828-1834).

After the death of King D. Sebastião in 1578 without leaving heirs, Portugal entered a succession crisis. The two main contenders for the throne were King Philip II of Spain, who was a nephew of D. Sebastião, and the Duke of Bragança, who was the legitimate heir to the throne. King Philip II of Spain invaded Portugal in 1580 and conquered the country. Angra do Heroísmo was the last city to surrender to Spanish forces. Following the conquest of Portugal, King Philip II of Spain appointed his son, the infante D. Filipe, as the viceroy of Portugal. Angra do Heroísmo served as the capital of the viceroyalty of Portugal until 1640 when Portugal regained its independence.

Later, during the Portuguese Civil War, a conflict between absolutist and liberal forces, the liberal forces, led by Queen D. Maria II, were based on Terceira Island, an important center of the Portuguese liberal movement. In 1830, liberal forces defeated absolutist forces in the Battle of Praia da Vitória, which took place on Terceira Island. Following the victory, Queen D. Maria II established her residence in Angra do Heroísmo and proclaimed the city as the capital of Portugal. Angra do Heroísmo served as the capital of Portugal for only a few months until Queen D. Maria II returned to Lisbon in 1831.

Another remarkable historical fact is related to the Battle of Salga in 1583, a time when Portugal was under Spanish rule, and Terceira Island was one of the last Portuguese territories to resist Spanish occupation. In this historic event, a prominent figure emerged, Brianda Pereira, a strong and fearless woman. She led a group of women who released a herd of bulls on Salga Beach, where the Spanish soldiers were landing. The bulls attacked the Spanish soldiers, causing panic and confusion. The Portuguese took advantage of this opportunity to attack and defeat the Spanish. Brianda Pereira's contribution to the Battle of Salga was crucial to the Portuguese victory. She is considered a heroine of the Azorean resistance against Spanish rule.

In recent history, the island was also the site of the Lajes Summit, a diplomatic meeting held on March 16, 2003, at the Lajes Air Base. The meeting included the leaders of the United States, the United Kingdom, Spain, and Portugal, and its objective was to discuss the situation in Iraq and the possibility of military intervention to remove President Saddam Hussein.